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Sample Size Definition in Cochrane Hepato-Biliary Trials

The recruitment status of this study is unknown. The completion date has passed and the status has not been verified in more than two years.
Verified January 2015 by Azienda Ospedaliera di Lecco.
Recruitment status was:  Recruiting
Information provided by (Responsible Party):
Agostino Colli, Azienda Ospedaliera di Lecco Identifier:
First received: May 14, 2012
Last updated: January 13, 2015
Last verified: January 2015

Sample size definition provides important information, allowing the groundwork for transparent reporting. The sample predefinition allows the trial to be large enough to be able to address the question that is being asked.

The aim of the present study is to assess, in all the randomized controlled trials (RCT) included in the Cochrane Hepato-Biliary Group (CHBG) systematic reviews, the quality of reporting sample size the accuracy of the calculations, the accuracy of the a priori assumptions and the effect on the agreement with pooled results in meta-analyses.

Definition of Sample Size in Randomized Clinical Trial Assessing Liver Disease

Study Type: Observational
Study Design: Time Perspective: Prospective
Official Title: Review: Analysis of the Sample Size Definitions in the Randomized Clinical Trials Included in Systematic Reviews of the Hepato-biliary Group of the Cochrane Collaboration

Resource links provided by NLM:

Further study details as provided by Azienda Ospedaliera di Lecco:

Primary Outcome Measures:
  • proportion of reported sample size definitions [ Time Frame: up to three months after retrievement and inclusion of all studies ]
    number of included studies with explicit sample size definition/ number of included studies

Estimated Enrollment: 250
Study Start Date: July 2012
Estimated Study Completion Date: April 2016
Estimated Primary Completion Date: December 2015 (Final data collection date for primary outcome measure)
Detailed Description:

The investigators aim to answers to these questions


  • How large a proportion of recent hepato-biliary RCTs does report an adequate sample size estimation?
  • Primary outcome is clearly defined ? and clinical meaningful ?
  • Is the sample size calculation based on the primary outcome ?
  • Does the predicted control event rate coincide with the actual one?
  • What is the predicted intervention effect?
  • Are confidence intervals of primary outcome results reported? Is there evidence of difference between the two arms?
  • Is the effect size so large (> 50%) to suggest post hoc definition ?
  • What is the accepted error alpha and beta?
  • How many study do not comply with the usual rule of alpha = 5% beta = 20%?
  • Do trials with planned sample size do better than those without ? Is the overlap between CI results less frequent ? Are their results more frequently "statistical" significant ?
  • Do trials with planned sample more frequently agree with pooled results in meta-analysis ?
  • Has the protocol been published in a public register before inclusion of participant?
  • How often is intention-to-treat analyses employed as primary analysis?
  • How often is the trial results resting upon subgroup analysis?


All the randomized clinical trials included in a systematic review of the Cochrane Hepato-biliary group (according to my search 272) were detected and retrieved. Only two arm, parallel group superiority randomised controlled trials with a single primary outcome.

The investigators excluded reports for which the study design was factorial, cluster, or crossover For all selected articles, the investigators systematically retrieved and assessed the full published report of the trial, any extra material or appendices available online, the study design article, if cited, and the details of online registration of the trial, if mentioned. A standardised data collection form was generated on the basis of a review of the literature and a priori discussion and tested by the research team.


Ages Eligible for Study:   Child, Adult, Senior
Sexes Eligible for Study:   All
Accepts Healthy Volunteers:   No
Sampling Method:   Non-Probability Sample
Study Population
Randomized clinical trials included in systematic reviews of the hepato-biliary Group of the Cochrane Collaboration

Inclusion Criteria:

  • Two arms, parallel group superiority randomised controlled trials with a single primary outcome,

Exclusion Criteria:

  • Reports for which the study design was factorial, cluster, or crossover
  Contacts and Locations
Choosing to participate in a study is an important personal decision. Talk with your doctor and family members or friends about deciding to join a study. To learn more about this study, you or your doctor may contact the study research staff using the Contacts provided below. For general information, see Learn About Clinical Studies.

Please refer to this study by its identifier: NCT01604720

Contact: agostino colli, MD +390341489670
Contact: giovanni casazza, PhD +390250319653

Medicine Department A.Manzoni Hospital Recruiting
Lecco, Italy, I 23900
Contact: agostino colli, MD    +390341489670   
Contact: pietro pozzoni, MD    +390341489687   
Sub-Investigator: pietro pozzoni, MD         
Sponsors and Collaborators
Azienda Ospedaliera di Lecco
Principal Investigator: agostino colli, MD AO provincia di lecco
  More Information

Responsible Party: Agostino Colli, Head of Internal Medicine Department AO provincia di Lecco, Azienda Ospedaliera di Lecco Identifier: NCT01604720     History of Changes
Other Study ID Numbers: AOLecco002
Study First Received: May 14, 2012
Last Updated: January 13, 2015

Keywords provided by Azienda Ospedaliera di Lecco:
sample size
liver disease

Additional relevant MeSH terms:
Liver Diseases
Digestive System Diseases processed this record on May 23, 2017